All that day Abimelek pressed his attack against the city until he had captured it and killed its people. Then he destroyed the city and scattered salt over it. (9:45)
Abimelek became a king with the help of the citizens of Shechem, but when they were against him, he attacked them and destroyed the city, having scattered salt over it. Something interesting is to be seen here: scattering salt over his own people and city. Our traditional culture of scattering salt is also shown here as a cursing act over others or stopping devils from coming into their houses or areas.
However, saltiness has different meaning and value in the bible.
According to Leviticus(레위기) chapter 2:12-13, 'You may bring them to the LORD as an offering of the first fruits, but they are not to be offered on the altar as a pleasing aroma. Season all your grain offerings with salt. Do not leave the salt of the covenant of your God out of your grain offerings; add salt to all your offerings.
Salt is one of the most essential mineral in life and its saltiness is one of the basic human tastes. Moreover, it plays an important role of food preservation. And it is symbolized as being pure and sacred. In a nutshell, it means holy, pure, and sacred Christians.
If it loses its role, it becomes like this. "You are the salt of the earth. But if the salt loses its saltiness, how can it be made salty again? It is no longer good for anything, except to be thrown out and trampled by men. (Matthew 5:13)
Joshua 1: 8
Do not let this Book of the Law depart from your mouth; meditate on it day and night, so that you may be careful to do everything written on it. Then you will be prosperous and successful.